In this report by Bob Lang, a Billco Solution Specialist, identifies and explains the various applications of heat required for successful lamination practices. He answers often-asked questions like “Why is heat needed in the Pre-Press process?” and “What heating sources are being used in Pre-press Ovens?” This report was first presented first at the GANA Glass Fabrication Conference in 2005.
Why is heat needed in the Pre-Press process?
The primary goal is to quickly and every heat the Interlayer with minimal heating of the glass. This heating of the Interlayer results in the following events:
- Softening the Interlayer until it is just tacky enough to stick to the glass to prevent any movement (misalignment) of the glass and Interlayer as it passes through the first Nip Roll Press, where initial de-airing takes place?
- Continued softening of the Interlayer to a point where the peaks and valleys in the texture of the Interlayer are squished flat, permitting final de-airing of the laminate in the second Nip Roll Press.
- Sealing the edges of the laminate in the second Nip Roll Press simultaneously as the final de-airing takes place.
The template must be carefully controlled to prevent overheating of the glass, which can cause premature edge sealing of the glass to interlayer before all the air is pressed from the laminate. Premature edge sealing will result in the trapping of air bubbles inside the laminate, and rejection of the laminate.
What heating sources are being used in Pre-press Ovens?
Traditional Infrared Heating This heating is generally by round elements, similar to those used in a home oven. Heat is radiated 360° from the element, which requires the mounting of a secondary reflector to direct the heat to the laminate. Heating is accomplished by a “soaking” process of convection and conduction…whereby the air is heated, then the glass, and then the interlayer.